Incidental Intracranial Aneurysms Research Articles

Black blood MRI sequences in the acute management of ruptured and unruptured intracranial aneurysms

We present an illustrative case series in which high spatial resolution black blood (BB) MRI sequences were used as an adjunct in the acute management of intracranial aneurysms with diagnostic uncertainty regarding rupture status. Several acute management dilemmas are discussed including the surveillance of previously treated ruptured intracranial aneurysms, identifying culprit lesion(s) amongst multiple ruptured intracranial aneurysms, and risk stratifying incidental unruptured intracranial aneurysms. We present our experience which supports the evaluation of this vessel wall imaging technique in larger multi-centre observational studies. MR imaging was performed on a 3.0 Tesla Siemens Somatom Vida system and sequences used included: Susceptibility Weighted Imaging, Diffusion Weighted Imaging & 3D T1 pre- and post-contrast-enhanced BB sequences.

Prevalence of unruptured intracranial aneurysms: impact of different definitions – the Tromsø Study

BackgroundManagement of incidental unruptured intracranial aneurysms (UIAs) remains challenging and depends on their risk of rupture, estimated from the assumed prevalence of aneurysms and the incidence of aneurysmal subarachnoid haemorrhage....

The emergency department incidence of incidental intracranial aneurysm on computed tomography angiography (EPIC-ACT) study.

Subarachnoid hemorrhage has been traditionally ruled-out in the emergency department (ED) through computed tomography (CT) followed by lumbar puncture if indicated. Mounting evidence suggests that non-contrast CT with CT angiography (CTA) can safely rule-out subarachnoid hemorrhage and obviate the need for lumbar puncture, but adoption of this approach is hindered by concerns of identifying incidental aneurysms. This study aims to estimate the incidence of incidental aneurysms identified on CTA head and neck in an ED population. This was a health records review of all patients ≥ 18years who underwent CTA head and neck for any indication at four large urban tertiary care EDs over a 3month period. Patients were excluded if they underwent CT venogram only, had previously documented intracranial aneurysms, or had intracranial hemorrhage with or without aneurysm. Imaging reports were reviewed by two independent physicians before extracting relevant demographic (age, sex), clinical (CTAS level, CEDIS primary complaint) and radiographic (number, size, and location of aneurysms) information. The incidence rate of incidental aneurysms was calculated. A total of 1089 CTA studies were reviewed with a 3.3% (95% CI 2.3-4.6) incidence of incidental intracranial aneurysms. The median size of incidental aneurysms was 4mm (0.7-11) and 10 (27.7%) patients had multiple aneurysms. Patients with incidental aneurysms did not differ based on mean age, sex, and CTAS levels. The "risk" of discovering an incidental aneurysm is 3.3%. Clinicians should not be deterred from using CTA in the appropriate clinical settings. These estimates can inform shared decision-making conversations with patients when comparing subarachnoid hemorrhage rule-out options.

Clinical Implementation of 7T MRI for the Identification of Incidental Intracranial Aneurysms versus Anatomic Variants.

Most unruptured intracranial aneurysms can be adequately characterized using 1.5T and 3T MR imaging. Findings in a subgroup of patients can remain unclear due to difficulties in distinguishing aneurysms from vascular anatomic variants. We retrospectively analyzed clinical data from 30 patients with suspected incidental aneurysms on 3T MR imaging who underwent 7T MR imaging. In all 30 cases, the differentiation of an aneurysm versus a vascular variant could be achieved. In 20 cases (66%), the initial suspected diagnosis was revised. Our findings suggest that 7T MR imaging provides a clarification tool for the group of patients with suspected unruptured intracranial aneurysms and diagnostic ambiguity after standard 3T MR imaging.

Numerical simulation of electroosmotic force on micropolar pulsatile bloodstream through aneurysm and stenosis of carotid

Smoking and hypertension are significant risk factors for atherosclerotic carotid artery disease, but also for intracranial aneurysms. The medical results suggest incidental intracranial aneurysms in patients with internal carotid artery (ICA) stenosis arteries. Which led to a study of the comparison between stenosis and aneurysm segments through the artery. A mathematical and numerical model for blood solidification and its rupture in a diseased artery is described in this paper. The interaction between the blood flow and a diseased arterial wall was formulated. The blood flow is formulated as a micropolar incompressible fluid with heat and mass transfer under the control of electro-osmotic and electromagnetic forces through an artery that contains stenosis and aneurysms. The approximation of mild stenosis is used to derive the governing flow equation, which is then solved using a method of finite difference. Particular attention is paid to the impact on axial velocity, flow rate, resistance impedance, and wall shear stress of geometrical parameters of the arterial wall and rheological blood parameters. In the instantaneous pattern of streamlines, the global behavior of blood is also investigated. Finally, the effect of all parameters on the blood flow through artery whose stenosis and aneurysm are investigated as a comparison of both segments.

Aneurysm Wall Enhancement Is Associated With Decreased Intrasaccular IL-10 and Morphological Features of Instability.

High-resolution vessel wall imaging plays an increasingly important role in assessing the risk of aneurysm rupture. To introduce an approach toward the validation of the wall enhancement as a direct surrogate parameter for aneurysm stability. A total of 19 patients harboring 22 incidental intracranial aneurysms were enrolled in this study. The aneurysms were dichotomized according to their aneurysm-to-pituitary stalk contrast ratio using a cutoff value of 0.5 (nonenhancing<0.5; enhancing≥0.5). We evaluated the association of aneurysm wall enhancement with morphological characteristics, hemodynamic features, and inflammatory chemokines directly measured inside the aneurysm. Differences in plasma concentration of chemokines and inflammatory molecules, morphological, and hemodynamic parameters were analyzed using the Welch test or Mann-Whitney U test. The concentration ΔIL-10 in the lumen of intracranial aneurysms with low wall enhancement was significantly increased compared to aneurysms with strong aneurysm wall enhancement (P=.014). The analysis of morphological and hemodynamic parameters showed significantly increased values for aneurysm volume (P=.03), aneurysm area (P=.044), maximal diameter (P=.049), and nonsphericity index (P=.021) for intracranial aneurysms with strong aneurysm wall enhancement. None of the hemodynamic parameters reached statistical significance; however, the total viscous shear force computed over the region of low wall shear stress showed a strong tendency toward significance (P=.053). Aneurysmal wall enhancement shows strong associations with decreased intrasaccular IL-10 and established morphological indicators of aneurysm instability.

Prevalence of Incidental Intracranial Aneurysms in Oncologic Patients

Prevalence of Incidental Intracranial Aneurysms in Oncologic Patients

Incidental Unruptured Intracranial Aneurysms Do Not Impact Outcome in Patients With Acute Cerebral Infarction

Background: This study was to examine the patients with acute cerebral infarction (ACI) treated at a single center over 9 years and who underwent Unruptured intracranial aneurysm (UIA) screening by three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA), and to explore the factors associated with outcomes.Methods: The outcome was the modified Rankin scale (mRS) score at 90 days after stroke onset. The outcome was classified into a good outcome (mRS score of 0–2 points) and poor outcome (mRS score of 3–6 points).Results: UIAs were found in 260 (6.5%) of 4,033 patients with ACI; 2,543 (63.1%) had a good outcome, and 1,490 (36.9%) had a poor outcome. There was no difference in outcomes between the two groups (P = 0.785). The multivariable analysis showed that age (OR = 1.009, 95%CI: 1.003–1.014, P = 0.003), diabetes (OR = 1.179, 95%CI: 1.035–1.342, P = 0.013), ischemic stroke history (OR = 1.451, 95%CI: 1.256–1.677, P < 0.001), and baseline NIHSS score (OR = 1.034, 95%CI: 1.018–1.050, P < 0.001) were independently associated with the 90-day outcomes in patients with ACI. The presence of incidental UIA was not associated with outcomes after ACI.Conclusions: Age, diabetes, ischemic stroke history, and baseline NIHSS score were independently associated with the early outcomes of patients with ACI.

Prevalence, predictors and prognosis of incidental intracranial aneurysms in patients with suspected TIA and minor stroke: a population-based study and systematic review

IntroductionUnruptured intracranial aneurysms (UIAs) are common incidental imaging findings, but there are few data in patients with transient ischaemic attack (TIA)/stroke. The frequency of UIA might be higher due to...

Prevalence of intracranial aneurysms among acute ischemic stroke patients.

Background: The prevalence of unruptured intracranial aneurysms varies with age, sex, and genetic diseases, including atherosclerotic diseases. The objectives of this study are to determine the prevalence of intracranial aneurysms among acute ischemic stroke patients and the clinical outcomes of the patients.Methods: The authors included patients with acute ischemic stroke within 7 days of onset. Demographic data, stroke subtypes, risk factors, and modified Rankin scale (mRS) scores at 6 months after stroke were collected. Magnetic resonance angiography was performed to diagnose intracranial aneurysms. The occurrence of aneurysmal subarachnoid hemorrhage (aSAH) was recorded during the follow-up at 6 months.Results: Thirteen (7%) of the 186 patients were found to have incidental intracranial aneurysms. Age and sex were not different between the patients with and without aneurysms (P > 0.999, P > 0.999). Ten patients (76.9%) had a saccular aneurysm. The most common site of the aneurysm was the cavernous part of the internal carotid artery (n = 6). Nine patients (69.2%) had very small (<4 mm) aneurysms. No aSAH was detected until 6 months after stroke. Favorable outcomes (mRS 0–2) at 6 months were not different between the patients with and without aneurysms (69.2% vs. 75.1%, P = 0.665).Conclusion: A higher prevalence of intracranial aneurysms was observed among acute ischemic stroke patients than among the general population. However, the variability of the general population should be considered. The functional outcomes of acute ischemic stroke patients are not affected by the presence of an intracranial aneurysm.

LO54: Emergency department prevalence of intracranial aneurysm on computed tomography angiography (EPIC-ACT)

Introduction: Evidence is accumulating that a CT plus a CT angiogram (CTA) of the head and neck may be adequate to rule out subarachnoid haemorrhage (SAH) in patients with a thunderclap headache, thus potentially negating the need for lumbar puncture. One of the most widely cited objections to this strategy is the fear of detecting “incidental asymptomatic aneurysms,” lesions seen on angiography that are not in fact the cause of the patient's symptoms. Currently existing data on the background rate of aneurysms are based on cadaveric studies, invasive angiography, or MRI, and thus does not reflect the true rate of incidental aneurysms that would be detected using a CT plus CTA strategy. This study characterizes the rate of incidental aneurysms identified on CTA in an emergency department population. Methods: In this multicentre retrospective cohort study we analyzed the electronic medical records of all emergency department patients ≥ 18 years of age who underwent CTA of the head and neck over a two month period across four urban tertiary care emergency departments. Two independent reviewers evaluated the final radiology reports and extracted relevant data. The primary outcome of interest was the presence of incidental intracranial aneurysm, defined as a newly diagnosed aneurysm not associated with evidence of acute hemorrhage. Secondary outcomes included aneurysm location and size. Results: Of 739 charts meeting inclusion criteria, incidental intracranial aneurysms were detected in 21 cases or 2.85% (95% confidence interval, 1.77 - 4.32). An additional 20 aneurysms were identified but excluded from the analysis as they were previously known (n = 9) or were associated with evidence of acute hemorrhage (n = 11) and thus were not considered incidental. Of 21 patients with identified incidental aneurysms, 7 had multiple aneurysms. The most common aneurysm sites were internal carotid artery (n = 13), middle cerebral artery (n = 6) and anterior cerebral artery (n = 4). The average size of incidental aneurysm was 4.1 mm. Conclusion: The rate of incidental intracranial aneurysm among emergency department patients undergoing CTA of the head and neck is lower than many previously described estimates obtained through invasive angiography and MRI studies. To our knowledge, this is the first study on the prevalence of incidental intracranial aneurysms in an emergency department specific population and may therefore help guide clinicians when considering using a CT plus CTA rule out strategy for patients presenting with acute headache suspicious for SAH.

A rare case report of extensive extracranial internal carotid artery aneurysm and its endovascular management

Aneurysms of the extracranial carotid arteries can occur as a result of atherosclerotic degeneration, traumatic injury, dissection, or local infection or as a complication after carotid endarterectomy. Extracranial carotid artery aneurysm (ECAA) is an uncommon but important clinical entity. Carotid aneurysms are extremely rare in comparison with atherosclerotic occlusive disease of the same location. These aneurysms are also rare in comparison with aneurysms involving the intracranial carotid arteries and their branches. The reported incidence of incidental intracranial aneurysms discovered in autopsy studies ranges from 0.8% to 18%. The incidence of ECAA is largely unknown, but it represents only 1%–1.5% of procedures performed for extracranial cerebrovascular disease at major referral centers.

P.114 Headache outcomes after treatment of unruptured intracranial aneurysms: systematic review and meta-analysis

Background: Headaches are a major cause of disability and healthcare cost worldwide. When investigating headaches etiology, incidental unruptured intracranial aneurysms are often considered unrelated. We conducted a systematic review and meta-analysis to assess headaches outcomes (severity) after treatment of unruptured intracranial aneurysm. Methods: MEDLINE and EMBASE were systematically reviewed. Results: The data from eligible studies (n=7) was extracted and analyzed. 309 nonduplicated patients provided patient-level data for analysis. All studies used the 10-point numeric rating scale (NRS). 88% of patients were treated with endovascular technique. Overall, the observed effect estimate under a random effects model was found to be a standard mean difference in pre- and post-intervention headache severity of -0.448 (95% CI: -0.566 to -0.329). No significant heterogeneity was noted. No significant publication bias was demonstrated. Conclusions: This is the first and largest systematic review assessing postoperative headache outcomes after treatment of unruptured intracranial aneurysm. A significant reduction in headache intensity after treatment is observed in the current published literature. This study highlights an interesting clinical phenomenon that still warrants scientific effort before it can influence clinical practice. We encourage future study to stratify headache outcomes by aneurysm size, location and treatment modality.

Unruptured intracranial aneurysms in children: 18 years' experience in a tertiary care pediatric institution.

There are little data in the literature on the characteristics and natural history of unruptured intracranial aneurysms in children. The authors analyzed their experience with unruptured intracranial aneurysms in the pediatric population at their tertiary care pediatric institution over the last 18 years. The first objective was to assess the imaging characteristics and natural history of these aneurysms in order to help guide management strategies in the future. A second objective was to evaluate the frequency of an underlying condition when an incidental intracranial aneurysm was detected in a child. The authors conducted a Research Ethics Board-approved retrospective review of incidental intracranial aneurysms in patients younger than 18 years of age who had been treated at their institution in the period from 1998 to 2016. Clinical (age, sex, syndrome) and radiological (aneurysm location, type, size, thrombus, mass effect) data were recorded. Follow-up imaging was assessed for temporal changes. Sixty intracranial aneurysms occurred in 51 patients (36 males, 15 females) with a mean age of 10.5 ± 0.5 years (range 9 months-17 years). Forty-five patients (88.2%) had a single aneurysm, while 2 and 3 aneurysms were found in 3 patients each (5.8%). Syndromic association was found in 22 patients (43.1%), most frequently sickle cell disease (10/22 [45.5%]). Aneurysms were saccular in 43 cases (71.7%; mean size 5.0 ± 5.7 mm) and fusiform in the remaining 17 (28.3%; mean size 6.5 ± 2.7 mm). Thirty-one aneurysms (51.7%) arose from the internal carotid artery (right/left 1.4), most commonly in the cavernous segment (10/31 [32.3%]). Mean size change over the entire follow-up of 109 patient-years was a decrease of 0.6 ± 4.2 mm (range -30.0 to +4.0 mm, rate -0.12 ± 9.9 mm/yr). Interval growth (2.0 ± 1.0 mm) was seen in 8 aneurysms (13.3%; 4 saccular, 4 fusiform). An interval decrease in size (8.3 ± 10.7 mm) was seen in 6 aneurysms (10%). There was an inverse relationship between aneurysm size and growth rate (r = -0.82, p < 0.00001). One aneurysm was treated endovascularly with internal carotid artery sacrifice. Unruptured pediatric intracranial aneurysms are most frequently single but can occur in multiples in a syndromic setting. None of the cases from the study period showed clinical or imaging signs of rupture. Growth over time, although unusual and slow, can occur in a proportion of these patients, who should be identified for short-term imaging surveillance.

Aneurysm wall enhancement in black blood MRI correlates with aneurysm size. Black blood MRI could serve as an objective criterion of aneurysm stability in near future.

The increasing number of incidental intracranial aneurysms creates a dilemma of which aneurysms to treat and which to observe. Clinical scoring systems consider risk factors for aneurysm rupture however objective parameters for assessment of aneurysms stability are needed. We retrospectively analysed contrast enhancing behaviour of un-ruptured aneurysms in the black blood magnetic resonance imaging (MRI) in N=71 patients with 90 aneurysms and assessed correlation between aneurysm wall contrast enhancement (AWCE) and aneurysm anatomy and clinical scoring systems. AWCE is associated with aneurysm height and height to width ratio in ICA aneurysms. AWCE is correlated to larger aneurysms in every anatomical location evaluated. However the mean size of the contrast enhancing aneurysms is significantly different between anatomical localizations indicating separate analyses for every artery. Clinical scoring systems like PHASES and UIATS correlate positively with AWCE in black blood MRI. MRI aneurysm wall contrast enhancement is a positive predictor for aneurysm instability and should be routinely assessed in follow up of incidental aneurysms. Aneurysms smaller than 7 mm with AWCE should be followed closely with focus on growth, as they may be prone to growth and rupture.

Preoperative Digital Subtraction Angiography in Incidental Unruptured Intracranial Aneurysms : How Much is too Much?

Digital subtraction angiography (DSA) is deemed necessary to precisely visualize intracranial aneurysms and define individual treatment strategies. In patients with unruptured intracranial aneurysms (UIA) who were diagnosed by MRI, afour-vessel DSA is usually performed to detect additional aneurysms. This study aimed to evaluate whether the evaluation of all vessels beyond the aneurysm-harboring artery is really necessary. Patients with an UIA that was detected on MRA (TOF/ceMRA) were prospectively included. All patients underwent afour-vessel DSA (including 3D-DSA) and two experienced neuroradiologists independently analyzed the MRI sequences before DSA. The number of aneurysms, size and anatomic localization were documented and correlated with the angiographic findings. The DSA revealed atotal of 134 aneurysms in 106 patients. Overall sensitivity and negative predictive value of MRA were 95.6% and 95.6%, respectively. In patients with multiple (≥2) aneurysms, 4very small aneurysms <3 mm in the A2 segment, posterior communicating artery (PcomA), extradural internal carotid artery (ICA) were missed with MRI alone. In one patient with an ICA aneurysm, an additional small MCA bifurcation aneurysm was overlooked by MRA but detected by DSA. The periprocedural complication rate was 0.9%. The rate of aneurysms that were detected by DSA but not by MRA was very low, thus potentially justifying visualization of the vessel harboring aneurysm alone; however, the four-vessel angiography detected further small aneurysms in patients with multiple aneurysms and therefore seems to be indicated in this specific subgroup. This approach has the potential to reduce the risk of complications, the intervention time and thus radiation exposure.

Prevalence of Incidental Clinoid Segment Saccular Aneurysms

Clinoid segment aneurysms are cerebral vascular lesions recently described in the neurosurgical literature. They arise from the clinoid segment of the internal carotid artery, which is the segment limited rostrally by the dural carotid ring and caudally, by the carotid-oculomotor membrane. Even although clinoid segment aneurysms represent a common incidental finding in magnetic resonance studies, its prevalence has not been yet reported. To determine the prevalence of incidental clinoid segment saccular aneurysms diagnosed by magnetic resonance imaging as well as their anatomic architecture and their association with smoking, arterial hypertension, age, and sex of patients. A total of 500 patients were prospectively studied with magnetic resonance imaging time-of-flight sequence and angioresonance with contrast material, to search for incidental saccular intracranial aneurysms. The site of primary interest was the clinoid segment, but the presence of aneurysms in any other location was determined for comparison. The relation among the presence of clinoid segment aneurysms, demographic factors, and secondary diagnosis of arterial hypertension, smoking, and other vascular/neoplastic cerebral lesions was analyzed. We found a global prevalence of incidental aneurysms of 7% (95% confidence interval, 5-9), with a prevalence of clinoid segment aneurysms of 3% (95% confidence interval, 2-4). Univariate logistic regression analysis showed a statistically significant relationship among incidental aneurysms, systemic arterial hypertension (P= 0.000), and smoking (P= 0.004). In the studied population, incidental clinoid segment aneurysms constitute the variety with highest prevalence.

The risk of intravenous thrombolysis-induced intracranial hemorrhage in Taiwanese patients with unruptured intracranial aneurysm.

BackgroundThe presence of an intracranial aneurysm is contraindicated to recombinant tissue plasminogen activator (r-tPA) treatment for acute ischemic stroke. However, it is difficult to exclude asymptomatic intracranial aneurysms by using conventional, noncontrast head computed tomography (CT), which is the only neuroimaging suggested before r-tPA. Recent case reports and series have shown that administering r-tPA to patients with a pre-existing aneurysm does not increase the bleeding risk. However, Asians are known to have a relatively higher bleeding risk, and little evidence is available regarding the risk of using r-tPA on Asian patients with intracranial aneurysms.MethodsMedical records from the Shuang Ho hospital stroke registration between July 2010 and December 2014 were retrospectively reviewed, and 144 patients received r-tPA. Unruptured intracranial aneurysms were detected using CT, or magnetic resonance or conventional angiography after r-tPA. The primary and secondary outcomes were the difference in overall intracranial hemorrhage (ICH) and symptomatic ICH after r-tPA. The differences were analyzed using Fisher’s exact or Mann–Whitney U tests, and p < 0.05 was defined as the statistical significance.ResultsA total of 144 patients were reviewed, and incidental unruptured intracranial aneurysms were found in 11 of them (7.6%). No significant difference was observed in baseline demographic data between the aneurysm and nonaneurysm groups. Among patients with an unruptured aneurysm, two had giant aneurysms (7.7 and 7.4 mm, respectively). The bleeding risk was not significant different between aneurysm group (2 out of 11, 18%) with nonaneurysm group (7 out of 133, 5.3%) (p = 0.14). None of the patients with an unruptured aneurysm had symptomatic ICH, whereas one patient without an aneurysm exhibited symptomatic ICH.ConclusionsThe presence of an unruptured intracranial aneurysm did not significantly increase the risk of overall and symptomatic ICH in Taiwanese patients after they received r-tPA.

Aneurysms in neurofibromatosis type 2: Evidence for vasculopathy?

There have been anecdotal reports of vasculopathy associated with Neurofibromatosis Type 2 (NF2). Given the increasing use of bevacizumab, a vascular endothelial growth factor inhibitor which results in an increased risk of bleeding, it is important to ascertain if there is a predisposition to vascular abnormalities in NF2. In our unit NF2 patients undergo annual MRI brain and internal auditory meatus imaging. We noted incidental intracranial aneurysms in some patients and sought to determine the prevalence of intracranial aneurysms in our cohort of NF2 patients. We conducted a retrospective audit of the MRI images of 104 NF2 patients from 2014 to 2016. Axial T2 brain MRI images were assessed for vascular abnormalities by two neuroradiologists blinded to patient's clinical details. Intracranial aneurysms were detected in four patients and an aneurysm clip related to previous surgery was noted in one additional patient. Using standard MRI imaging sequences alone we provide evidence of intracranial aneurysms in 4.4% of our cohort. This compares with an estimated overall prevalence of 3% in the general population. We discuss these findings as well as other evidence for a vasculopathy associated with NF2.

Computational fluid dynamics analysis of flow reduction induced by flow-diverting stents in intracranial aneurysms: a patient-unspecific hemodynamics change perspective

Background and purposeFlow-diverter stents (FDSs) have been used effectively to treat large neck and complex saccular aneurysms on the anterior carotid circulation. Intra-aneurysmal flow reduction induces progressive aneurysm thrombosis in...